An aircraft turbine engine typically includes an inlet guide vane assembly. The inlet guide vane assembly includes an annular outer frame, a coaxial annular inner frame, and multiple aircraft engine inlet guide vanes (sometimes referred to herein as “guide vanes” for brevity). The guide vanes are mounted between the inner and outer frames such that they extend radially from the inner frame to the outer frame and are circumferentially arranged around the common axis of the inner and outer frames. The inlet guide vane assembly is mounted between the leading edge of the inlet cowl of the nacelle of the engine and the turbomachinery of the engine so that the guide vanes are circumferentially arranged around the rotational axis of the engine. The guide vanes are shaped, positioned, and oriented to direct air flow to provide a desired air flow pattern into the turbomachinery of the engine during flight.
FIG. 1A shows a prior art aircraft turbine engine 1 including an inlet guide vane assembly 2 including multiple guide vanes 10. FIG. 1B shows one of the prior art guide vanes 10 having a radial dimension L. The guide vane 10 includes a leading edge member 11, a trailing edge member 14, and a body member 13 between the leading edge member 11 and the trailing edge member 14 and including opposing side walls that connect the leading edge member 11 and the trailing edge member 14. The guide vane 10 is attached to the inner and outer frames such that its radial dimension L extends between the inner and outer frames. The guide vane 10 is oriented so that while the aircraft is flying the external air flow EF impinges on and flows downstream past the leading edge member 11 of the guide vane 10.
When an aircraft flies in certain atmospheric conditions (like cold weather and heavy cloud cover or fog), ice tends to form and build up on parts of the aircraft on which air impinges, such as the guide vanes. The ice build-up partially (or sometimes completely) fills the gaps between adjacent guide vanes. This degrades the performance of the engine by reducing air intake and/or causing the guide vanes to provide an undesired air flow pattern. The engine is also susceptible to severe damage if a large enough chunk of ice breaks off of a guide vane, travels into the turbomachinery, and contacts its moving components (such as the turbine or the compressor blades).
Even if the leading edge member of a guide vane is heated enough to melt the built-up ice into water, the external air flow forces that water to travel downstream off of the leading edge member and onto the body member of the guide vane. Since the water no longer contacts the warm leading edge member, the water promptly refreezes, and ice build-up resumes. This phenomenon is called runback icing, and simply shifts the ice formation and build-up problem downstream from the leading edge member.